package samples.spring.step2.beans;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;

import java.math.BigInteger;
import java.security.MessageDigest;

/**
 * @author Zi Lai Ye
 * @date 2017/4/12
 */
public class PasswordPostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof PasswordDecodable) {
            PasswordDecodable passwordDecodable = (PasswordDecodable) bean;
            String encodedPassword = passwordDecodable.getEncodedPassword();
            String decodePassword = getMD5(encodedPassword);
            passwordDecodable.setDecodedPassword(decodePassword);
        }
        return bean;
    }

    /**
     * 对字符串md5加密
     *
     * @param str
     * @return
     */
    public static String getMD5(String str) {
        try {
            // 生成一个MD5加密计算摘要
            MessageDigest md = MessageDigest.getInstance("MD5");
            // 计算md5函数
            md.update(str.getBytes());
            // digest()最后确定返回md5 hash值，返回值为8为字符串。因为md5 hash值是16位的hex值，实际上就是8位的字符
            // BigInteger函数则将8位的字符串转换成16位hex值，用字符串来表示；得到字符串形式的hash值
            return new BigInteger(1, md.digest()).toString(16);
        } catch (Exception e) {
            return str;
        }
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
}
